The utilization of renewable raw materials has been considered as one of the “green chemistry” approaches that can contribute to sustainable development. Metzger, et al., C. R. Chim., 2004, 7, 569. Plant oils, naturally occurring triglycerides of fatty acids, make up the greatest proportion of the current consumption of renewable feedstocks used to prepare biobased polymers. Meier, et al., Chem. Soc. Rev., 2007, 36, 1788; Baumann, et al., Angew. Chem. Int. Ed. Engl. 1998, 27, 41; Biermann, et al., Angew. Chem. Int. Ed., 2000, 39, 2206; Khot, et al., J. Appl. Polym. Sci., 2001, 82, 703. Carbohydrates are another important class of renewable sources of green materials, and the versatile industrial work of transforming low molecular weight carbohydrates (e.g. mono- and di-saccharides) into products as the potential to replace petrochemical products is very attractive. F. W. Lichtenthaler and S. Peters, C. R. Chim., 2004, 7, 65-90.
Cationic UV curable coatings account for only about 8% of all the UV-coatings used in industry (Gu, et al., J. Coat. Technol. 2002, 74, 49.) primarily due to fewer types of cationic polymerizable monomers and oligomers available in the market (Zou, et al., Macromol. Chem. Phys. 2005, 206, 967). The three major types of epoxides used are silicon-containing epoxides, epoxidized seed oils (soybean or linseed oils) and cycloaliphatics. The seed oil epoxides are synthesized from renewable natural resources. A factor that prevents the extensive use of epoxidized oils is the relative low reactivity of the internal epoxy groups (Zou, et al., Macromol. Chem. Phys. 2005, 206, 967 and Sangermano, et al., J. Mater. Sci. 2002, 37, 4753). There remains, however, a need to explore new processes to broaden the applications of the seed oil epoxides. In recent years there has been growing interest in using vegetable oils as raw materials in resin production.
Vegetable oils are derived from the seeds of various plants and are chemically triglycerides of fatty acids. That is, vegetable oils consist of three moles of fatty acids esterified with one mole of glycerol. As shown below in Formula I, fatty acids are linear carboxylic acids having 4 to 28 carbons and may be saturated or ethylenically unsaturated.

Different plants produce oils having differing compositions in the fatty acid portion of the oil. Naturally-occurring vegetable oils are by definition mixtures of compounds, as are the fatty acids comprising them. They are usually either defined by their source (soybean, linseed) or by their fatty acid composition. A primary variable that differentiates one vegetable oil from another is the number of double bonds in the fatty acid; however, additional functional groups can be present such as hydroxyl groups in castor oil and epoxide groups in vernonia oil. Table 1 below identifies the typical fatty acid composition for some commonly occurring vegetable oils.
TABLE 1Fatty AcidUnsaturationCoconutCornSoybeanSafflowerSunflowerLinseedCastorTall Oil FATungC12Lauric044C14Myristic018C16Palmitic01113118116254C18Stearic0644364131Oleic1729251329227468Ricinoleic187Linoleic2254517552163414Linolenic39125233Eleaosteric380Iodine7.5-10.5103-128120-141140-150125-136155-20581-91165-170160-175Value
Vegetable oils have been used extensively as binder systems in paints and coatings for centuries. Drying oils, such as linseed oil, have been used as a component of paint binders since drying oils can be converted into a tack free film upon reaction with atmospheric oxygen in a process called autoxidation. Vegetable oils have also been used in the synthesis of alkyd resins by combining the fatty acids in the oils with other monomers to form a fatty acid containing polyester resin. Vegetable oils also have several advantages of being renewable, biodegradable and hence have less impact on the environment. Vegetable oils can impart desirable flexibility and toughness to the otherwise brittle cycloaliphatic epoxide system. Wan Rosli, et al., Eur. Polym. J. 2003, 39, 593.
Sucrose, β-D-fructofuranosyl-α-D-glucopyranoside, is a disaccharide having eight hydroxyl groups. The combination of sucrose and vegetable oil fatty acids to yield sucrose esters of fatty acids (SEFA) as coating vehicles was first explored in the 1960s. Bobalek, et al., Official Digest, 1961, 453; Walsh, et al., Div. Org. Coatings Plastic Chem., 1961, 21, 125. However, in these early studies, the maximum degree of substitution (DS) was limited to about 7 of the available 8 hydroxyl groups. The resins do not appear to have been commercialized at that time. In the early 2000s, Proctor & Gamble (P&G) Chemicals developed an efficient process for industrially manufacturing SEFAs commercially under the brand name SEFOSE with a high DS of at least 7.7 (representing a mixture of sucrose hexa, hepta, and octaesters, with a minimum of 70% by weight octaester) (U.S. Pat. Nos. 6,995,232; 6,620,952; and 6,887,947), and introduced them with a focus on marketing to the lubricant and paint industries. Due to their low viscosities (300-400 mPa·s), SEFOSE sucrose esters can be used as binders and reactive diluents for air-drying high solids coatings. Formula II displays the possible molecular structure of a sucrose ester with full substitution. Procter and Gamble has reported a process to prepare highly substituted vegetable oil esters of sucrose using transesterification of sucrose with the methyl esters of sucrose. U.S. Pat. No. 6,995,232.

An epoxide group is a three-membered, cyclic ether containing two carbon atoms and one oxygen atom. An epoxide can also be called an oxirane. As in known in the art, an epoxy group has the structure shown in formula III in which R and R′ are organic moieties representing the remainder of the compound.

Epoxy resins are materials consisting of one or more epoxide groups. Due to the strained nature of the oxirane ring, epoxide groups are highly reactive and can be reacted with nucleophiles such as amines, alcohols, carboxylic acids. Thus, epoxy resins having two or more epoxy groups can be reacted with compounds having multiple nucleophilic groups to form highly crosslinked thermoset polymers. Oxiranes can also be homopolymerized. Epoxy resins having two or more epoxy groups can be homopolymerized to form highly crosslinked networks. Crosslinked epoxy resins are used in a large number of applications including coatings, adhesives, and composites, among others. The most commonly used epoxy resins are those made from reacting bisphenol-A with epichlorohydrin to yield difunctional epoxy resins.
Epoxidation is one of the most important and useful modifications using the double bonds of ethylenically unsaturated fatty compounds (Scheme 1 below), since epoxide is a reactive intermediate to readily generate new functional groups. Ring-opening of epoxide via nucleophilic addition leads to a large number of products, such as diol, alkoxy alcohol (ether alcohol), hydroxy ester (ester alcohol), amino alcohol, and others. Through epoxide opening of epoxidized soybean oil using alcohols, triglyceride polyols intended for application in polyurethanes have been successfully prepared by Petrovic and co-works. U.S. Pat. Nos. 6,107,433 and 6,6867,435; and Zlatanić, et al., J. Polym. Sci., Part B: Polym. Phys., 2004, 42, 809.
Epoxide reaction with ethylenically unsaturated acids has been widely utilized to synthesize oil-based free-radical UV-curable coating resins by reacting acrylic acids with epoxidized vegetable oils (EVOs). LaScala, et al., J. Am. Oil Chem. Soc., 2002, 79, 59; LaScala, et al., Polymer, 2005, 46, 61; and Pelletier, et al. J. Appl. Polym. Sci., 2006, 99, 3218.
Epoxide groups, or oxirane groups, as discussed, can be synthesized by the oxidation of vinyl groups. Findley, et al., (JACS, 67, 412-414 (1945)) reported a method to convert the ethylenically unsaturated groups of triglyceride vegetable oils to epoxy groups, as shown in the scheme below. A number of other processes and catalysts have been developed to also achieve epoxidized oils in good yields.

Generally, while there are four techniques that can be employed to produce epoxides from olefinic molecules (Mungroo, et al., J. Am. Oil Chem. Soc., 2008, 85, 887), the in situ performic/peracetic acid (HCOOH or CH3COOH) process appears to be the most widely applied method to epoxidize fatty compounds. Scheme 2 displays the reaction mechanism, which consists of a first step of peroxyacid formation and a second step of double bond epoxidation. Recently, the kinetics of epoxidation of vegetable oils and the extent of side reactions was studied using an acidic ion exchange resin as catalyst and revealed that the reactions were first order with respect to the amount of double bonds and that side reactions were highly suppressed; the conversion of double bonds to epoxides was also high. Petrović, et al., Eur. J. Lipid Sci. Technol., 2002, 104, 293; and Goud, et al., Chem. Eng. Sci., 2007, 62, 4065. The catalyst, Amberlite IR 120, is an acidic ion exchange resin, a copolymer based on styrene (98 wt %) crosslinked by divinylbenzene (2 wt %). Its acidity is generated by sulfonic acid groups attached to the polymer skeleton.

Epoxides generated from the epoxidation of double bonds of ethylenically unsaturated fatty acids are known as internal epoxides—both carbons of the heterocyclic ring are substituted with another carbon. The most commonly used epoxy resins are the bisphenol-A diglycidyl ether resins. The epoxy groups on these resins are of the type known as external epoxides—three of the four substituent groups on the heterocyclic ring are hydrogen atoms. Since internal epoxides are much less reactive than external epoxides in most epoxy curing reactions, the roles traditionally assigned to epoxidized oils are as stabilizers and plasticizers for halogen-containing polymers (i.e. poly(vinyl chloride)) (Karmalm, et al., Polym. Degrad. Stab., 2009, 94, 2275; Fenollar, et al., Eur. Polym. J., 2009, 45, 2674; and Bueno-Ferrer, et al., Polym. Degrad. Stab., 2010, 95, 2207), and reactive toughening agents for rigid thermosetting plastics (e.g. phenolic resins). Miyagawa, et al., Polym. Eng. Sci., 2005, 45, 487. It has also been shown that EVOs can be cured using cationic photopolymerization of epoxides to form coatings. Crivello, et al., Chem. Mater., 1992, 4, 692; Thames, et al., Surf. Coat. Technol., 1999, 115, 208; and Ortiz, et al., Polymer, 2005, 46, 1535.
Crivello reported the preparation of a number of epoxidized vegetable oils and their crosslinking using cationic photoinitiators. U.S. Pat. No. 5,318,808; Crivello, et al., Chem. Mater., 1992, 4, 692-699. In general, the coatings formed from photopolymerization were soft due to the low crosslink density obtained and the flexible aliphatic nature of the backbone of the vegetable oils. Epoxy-anhydride curing using epoxidized soybean oil (ESO) and dicarboxylic acid anhydrides in the presence of tertiary amine and imidazole as catalysts have also been studied (Rösch et al., Polymer Bulletin, 1993, 31, 679-685; Annelise, et al., Journal of the American Oil Chemists' Society, 2002, 79, 797-802) but there remains a need for improved epoxy-anhydride curing compositions.
The radiation curing industry has been using acrylated resins as the key components in coatings and inks. Bajpai, et al., Pigment & Resin Technology 2004, 33, 160. Acrylated soybean oils (ASO) takes up 90% of acrylated resin's market consumption due to its low cost and availability. Prantil, B. Journal of Oil and Colour Chemist's Association 2000, 83, 460. ASO resin is great for printing ink due to its excellent pigment wetting power. Bajpai, et al., Pigment & Resin Technology 2004, 33, 160. Furthermore, the acrylate groups in the molecules are able to participate in free-radical polymerization in the coating system. Bunker, et al., Journal of Polymer Science: Part A: Polymer Chemistry 2002, 40, 451-458. A need still remains for improved acrylated resins, particularly resins which can be derived from low-cost and renewable raw materials.